I just changed the speedo and rpm face plates from my 89 formula parts car w/ a 305 TPI to my 88 Trans am w/ a 305 H.O.? will my speedo be off now because my old speedo face plate only went to 120 and now it goes to 140? i dont think the speedo's r geared any diff. between the 2 cars because its all electronic. Will someone please answer my question thanks! Also if anyone needs parts look me up on Cardomain.com my user name is TADailyDriver or just look me up here http://www.cardomain.com/ride/2985577

You can't just swap the faces, or the speedo won't read right. You can however swap the entire cluster, and it will work fine.

how hard is it to swap the whole gauge? is it just a plug and go type of deal or do i have to recailbrate anything?

the cluster will interchange with no issues at all.
Just have to swap over the odometer

Yeah, swapping the cluster is pretty straight forward, it's all bolt on and plug-n-play. Its a little easier if you loosen the 2 large nuts under the dash that hold the steering column up. You don't have to remove them, but you can loosen them enough to drop the steering column down about an inch. Makes it easier to get the new cluster in. Also, swapping the odometer isn't required for it to work, unless you want the mileage to still read correctly.

Awsome guys thanks! the mileage on both cars are about the same so ill prolly swap them back to normal until the miles read the same! anyone know where i can get a set of heads for my car? not looking for anything to extreme! thanks again i appreciate it!
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also is that the same thing for the rpm gauge as well?

Yes, the tach will also swap with no problems, as long as theyre both V8 cars. A V6 tach won't read correctly on a V8, and vice-versa.

Hey welcome man. I like your idea of changing the rpm gauges. I already have the 140 speedo in my car cause it came with it.

Btw I'm that crazy guy on cardomain you talk to (Firehawk896)